PURPOSE: To enable the fuel pressure to be detected without providing a new mounting hole by placing a fuel pressure sensor, which combines a pulsation damping function, in the mounting hole for a pulsation damper.

CONSTITUTION: When the fuel pressure in a fuel chamber 55 is not more than a prescribed value, a traveling contact 7 is in contact with a fixed contact 8, and a lead wire 65 connected with a sensor and the like is conducting by means of a slide rod 6 and contacts 7, 8 with the earth side. When the pressure of fuel flowing in through an entry port 41 rises to more than the prescribed value, the fuel pushes a diaphragm 54 up against the force of a spring 50, and flows out from the chamber 55 through an exit port 42, and then flows in a delivery pipe 1. Hereupon, with the aid of a valve 57, the rod 6 is caused to ascend so that the contact 7 is separated from the contact 8 to make the lead wire 65 nonconductive with the earth side. The pulsation of the pressure in the pipe 1 caused by an additional spouting of the fuel is damped by the diaphragm 54, which is energized by the action of the spring 50. Thereby, a single device can be used both for damping the pulsation and for detecting the pressure.